Valve's "Perpetual Testing Initiative" has already been yielding results, and they provide evidence for the hypothesis that people still like playing Portal 2. Since the DLC's release on May 8, the company reports that over 35,000 user-created maps have been uploaded, which have been downloaded over 1.3 million times.

To celebrate this successful experiment, Valve has discounted several items on Steam, including, of course, Portal 2, which costs just $6.79 right now! Fellow Steam Workshop title Skyrim is on sale for $40.19, and several Workshop items within Team Fortress 2 can be found for 50% off.